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Category:   Application (Security)  >   GnuPG (Gnu Privacy Guard) Vendors:   Gnupg.org
(Turbo Linux Issues Fix) Re: GnuPG Public Key Encryption Program Can Execute Remotely Supplied Arbitrary Code During File Decryption
SecurityTracker Alert ID:  1001821
SecurityTracker URL:  http://securitytracker.com/id/1001821
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Jun 22 2001
Impact:   Execution of arbitrary code via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 1.0.5 and prior
Description:   Synergy Networks announced a vulnerability in the GnuPG public key encryption program that allows a remote user to cause the GnuPG client to execute arbitrary code.

It is reported that there is a format string vulnerability that can be triggered by attempting to decrypt a file with a specially crafted filename. This vulnerability can allow a remote user to cause arbitrary code to be executed on the host of the user that attempts the decryption.

The affected code reportedly exists in util/ttyio.c in the 'do_get' function, where there is a call to a function called 'tty_printf' (which ultimately results in a
vfprintf call) without a constant format string:

> tty_printf( prompt );

If GnuPG attempts to decrypt a file with a filename that does not end in ".gpg", that filename (without the extension) is copied to the prompt string. This allows a remote user to supply data to the format string.

Impact:   A remote user can cause arbitrary code to be executed by a GnuPG user that decrypts a file from the remote user.
Solution:   Turbo Linux has issued a fix. See the Source Message for the TurboLinux advisory.
Vendor URL:  www.gnupg.org/ (Links to External Site)
Cause:   Input validation error
Underlying OS:  Linux (Turbo Linux)

Message History:   This archive entry is a follow-up to the message listed below.
May 30 2001 GnuPG Public Key Encryption Program Can Execute Remotely Supplied Arbitrary Code During File Decryption



 Source Message Contents

Subject:  TLSA2001028 gnupg-1.0.6-1


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1



___________________________________________________________________________

                     Turbolinux Security Announcement

        Package: gnupg
        Vulnerable Packages: All Turbolinux versions previous to 1.0.6-1
        Date: 06/21/2001 5:00 PDT

        Affected Turbolinux platforms:  TL 6.5 Server,
                                        TL 6.1 Workstation,
                                        All Turbolinux versions
                                        6.0.5 and earlier

        Turbolinux Advisory ID#:  TLSA2001028

   References: http://www.i.cz/en/onas/tisk4.html

http://linuxtoday.com/news_story.php3?ltsn=2001-05-30-015-20-SC-PD

___________________________________________________________________________

Security holes have been discovered in the package gnupg, the GPG encryp-
tion program.  Please update this package in your installation as soon as 
possible.
___________________________________________________________________________

1. Problem Summary

   a. Format String Vulnerability
   
   	An indirect invocation of the function vfprintf() does not pass
      the argument "%s" as the first argument.  This allows for a filename
      to use format strings and may allow a user with malicious intent to
      invoke shell commands with the current user's privileges.

   b. Private Key Retrieval Vulnerability

        It has been determined that there are insufficient measures taken in
      protecting a user's secret key.  If an attacker has write access to a
      user's private key file, and is able to capture a message that is signed
      with that private key, he will be able to decipher the user's private
      key.  Note that this is done even without knowledge of the user's se-
      cret passphrase.
  
2. Solution

  Update the package from our ftp server by running the following command:

  rpm -Uvh ftp_path_to_filename

  Where ftp_path_to_filename is the following:

ftp://ftp.turbolinux.com/pub/updates/6.0/security/gnupg-1.0.6-1.i386.rpm

  The source RPM can be downloaded here:

ftp://ftp.turbolinux.com/pub/updates/6.0/SRPMS/gnupg-1.0.6-1.src.rpm

  **Note: You must rebuild and install the RPM if you choose to download
  and install the SRPM.  Simply installing the SRPM alone WILL NOT CLOSE
  THE SECURITY HOLE.

 Please verify the MD5 checksums of the updates before you install:

  MD5 sum                               Package Name
___________________________________________________________________________

  a336358f776e0dbbb9f495693386a193     gnupg-1.0.6-1.i386.rpm
  bb873783b676249cbf22a09b5bc56f4d     gnupg-1.0.6-1.src.rpm
___________________________________________________________________________

These packages are GPG signed by Turbolinux for security. Our key
is available here:

 http://www.turbolinux.com/security/tlgpgkey.asc

To verify a package, use the following command:

 rpm --checksig name_of_rpm

To examine only the md5sum, use the following command:

 md5sum name_of_rpm

**Note: Checking GPG keys requires RPM 3.0 or higher.

___________________________________________________________________________

You can find more updates on our ftp server:

   ftp://ftp.turbolinux.com/pub/updates/6.0/security/ 
   for TL6.x Workstation and Server security updates
  
Our webpage for security announcements:

   http://www.turbolinux.com/security

If you want to report vulnerabilities, please contact:

   security@turbolinux.com
___________________________________________________________________________

Subscribe to the Turbolinux Security Mailing lists:

  TL-security - A moderated list for discussing security issues
                Turbolinux products.
  Subscribe at http://www.turbolinux.com/mailman/listinfo/tl-security

  TL-security-announce - An announce-only mailing list for security
                         updates and alerts.

  Subscribe at:

      http://www.turbolinux.com/mailman/listinfo/tl-security-announce

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.4 (GNU/Linux)
Comment: pgpenvelope 2.10.0 - http://pgpenvelope.sourceforge.net/

iD8DBQE7MkIqcpw52/ZatwoRAmnAAJ9Kn4rA+PucUZd012AnHbErNqElQQCeNop+
MbgPRyogF+2awz9Hb80B4Lo=
=P3t7
-----END PGP SIGNATURE-----


 
 


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